Web guide

ABSTRACT

An improved web guide for paper wires or other webs is disclosed employing a duplex air-hydraulic cylinder unit constructed with a single piston in a cylindrical tube to move a guide roller. A web edge follower and mechanical linkage govern an air pressure valve for supplying, in response to sensed web misalignments, different pressures to the sides of the piston. This air pressure difference moves the cylinder housing coupled to the roller so as to correct the web misalignment. The piston includes a longitudinally extending oil zone between it and the bore walls and a hydraulic seal ring affixed to the cylindrical tube. The ring divides the oil zone into two chambers which change volume with piston movement. A restricted flow path between the chambers prevents overcorrection and promotes smooth motion of the piston and roller. This arrangement provides for automatic lubrication of the piston and simplified construction and operation of the web guide. The oil zone is preferably fed by oil taken from an air line lubricator unit to maintain the pressure in the oil zone at the same level as the air pressure.

United Stat BS Patent Fountain et al.

[ 1 Aug. 7, 1973 1 WEB GUIDE [75] inventors: Richard W. Fountain; Darrel D.

Johnson, both of Appleton, Wis.

[73 1 Assignee: Gilbert & Nash Company, Inc.,

Appleton, Wis.

22 Filed: Apr. 5, 1971 [21] Appl. No.: 131,011

[52] US. Cl 226/23, 92/8 [51] Int. Cl B65h 25/26 [58] Field of Search 226/22, 23, 15; 92/8, 9

[56] References Cited UNITED STATES PATENTS 2,013,665 9/1935 Messier 92/8 X 2,877,013 3/1959 Wendshuh et a1.

3,416,409 12/1968 Labat Primary ExaminerRichard A. Schacher Assistant ExaminerGene A. Church Attorney-Gary, Parker, Juettner, Pigott & Cullinan [57] ABSTRACT An improved web guide for paper wires or other webs is disclosed employing a duplex air-hydraulic cylinder unit constructed with a single piston in a cylindrical tube to move a guide roller. A web edge follower and mechanical linkage govern an air pressure valve for supplying, in response to sensed web misalignments, different pressures to the sides of the piston. This air pressure difference moves the cylinder housing coupled to the roller so as to correct the web misalignment. The piston includes a longitudinally extending oil zone between it and the bore walls and a hydraulic seal ring affixed to the cylindrical tube. The ring divides the oil zone into two chambers which change volume with piston movement. A restricted flow path between the chambers prevents overcorrection and promotes smooth motion of the piston and roller. This arrangement provides for automatic lubrication of the piston and simplified construction and operation of the web guide. The oil zone is preferably fed by oil taken from an air line lubricator unit to maintain the pressure in the oil zone at the same level as the air pressure.

4 Claims, 5 Drawing Figures WEB GUIDE FIELD OF THE INVENTION The present invention relates to an improved web guide of the type that may be used with paper forming wires or screens, blankets, or other traveling webs and is particularly concerned with an improved device for sensing misalignment ofthe web and for automatically realigning it.

BACKGROUND OF THE INVENTION The present invention is directed to an improvement in the web guide disclosed and claimed in US. Pat. No. 2,877,013 entitled Guide for a Traveling Web which issued on Mar. 10, 1959 in the names of Herbert L. Wendshul and David E. Lamon and is assigned to the assignee of the present invention.

Web guides of the Wendshul and Lamon type have functioned well and met with general commercial acceptance, especially in the paper making industry wherein large and extremely long continuous webs, flts and wires, are employed. These web guides realign the web by shifting one end of a roller that is carrying the web in response to the sensing of web misalignment by a mechanical follower. The alignment sensing device in response to a sensed misalignment, alters the position of a special valve which, in turn, supplies and removes air pressure from opposite ends of a piston in a cylinder. The piston is normally fixed and the cylinder housing is caused to move and carry along one end bearing of the web roll. In these prior art guides, two cylinders had to be employed in the same housing the air cylinder and a second hydraulic cylindrical tube parallel to that of the air pressure cylinder. This second cylinder was filled with oil and a restrictive flow passage was formed in the piston to allow oil to flow from one side to the other. The later cylinder served to damp the erratic movement tendencies of the piston or air cylinder and to prevent overcorrection.

This dual cylinder construction for the roll moving element, while working satisfactorily, required precision machining and fitting to insure that the cylinders were parallel. If these cylinders were not parallel, the pistons would bind. The requirement that both pistons be parallel lead to them being formed in the same housing in a side-by-side arrangement and thus limited the capacity of the power piston for a given housing size.

SUMMARY OF THE INVENTION In overcoming these drawbacks and for achieving other advantages, thepresentinvention provides an improvementin a web .guide ofthe above described type wherein the web-rollmovingelement is formed of a single cylinder that performs the functionsofthe prio'r two cylinders. This isaccomplished by includingan hydraupressure betweentheends of the piston results in mo tion damped by the oil forcedto flowfrom one sideof the seal to the other.

The hydraulic damping is achieved without any sacrifree in air piston size. This results in more power for the same size when compared with prior two cylinder units. Put another way, the present invention allows for smaller and simpler guide roll moving units for a given power requirement. The combined cylinder also has fewer seals and wearing parts resulting in economy of manufacture and maintenance. Furthermore, the unit is selflubricating by reason of the presence of the oil zone adjacent to the bore walls.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with the further advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a perspective view of a web guide in its environment of use;

FIG. 2 is a schematic drawing of the fluid systems and the power cylinder of the. web guide of FIG. 1, which schematic is useful in understanding the operation of the present invention;

FIG. 3 is a longitudinal sectional detailed power cylinder of FIG. 1;

FIG. 4 is a fragmentary transverse sectional view of the cylinder of FIGS. 1 and 3, as seen from the line 4-4 of FIG. 3; and

FIG. 5 is a fragmentary sectional view of a portion of the cylinder of FIGS. 1, 3 and 4 as seen from the line 5-5 of FIG. 4.

DETAILED DESCRIPTION Referring in detail to the drawings and especially FIG. 1, thereof,a web guide constructed in accordance with the present invention is there depicted and is generally designated by the numeral 10. The web guide .10 serves to guide a traveling web, indicated by the numeral 11, which may comprisea paperforming wire or screen,'a traveling blanket or other type of web or belt view of the l which it may be desired to maintain 'in a substantially constantpath during its travel. A guide roll 12 isemployed to control the lateral :mov'ement of the web. The roll 12 is disposed tranversely to theraxis'ofrthe web and the web will normally assume .a position such as to bring its longitudinal axis at rightangles to the axis of the .guide roll. Hence, by incliningthe axis-.of'the roll 12in one direction orthe other a force isexerted upon the web to move it laterally inla predetermined direction. 7

The web guide 10 comprising the present invention is directed to a mechanism which so inclines the-1011512 in response to an undesired lateral movement of the web, such inclination functioning to return the web IIO its desired path.

being journaled in a bearing .(not shown) which has .a

degree of freedom tomove as the axis of 1the.roll is :in-

clined. Such self-aligning bearings are well known in the art. The opposite endportion .o fthe axle lfiis journaled in a self-aligning bearing 14' which ismounted upon a movablecarriage 1 5 which. functionsitomove the bearing 14 so as toincline theaxis-ofzthe"roll :12 telative to its normal position.

The movable carriage is slidably mounted upon a stationary frame member 16 which is secured to a stationary portion of a paper making machine or the like (not shown). The movement of the carriage 15 is sub stantially parallel to the general direction of travel of the web and in order to restrain the carriage for movement in this direction, the upper portion of the carriage is provided with a groove which registers with a guide rib 19 carried by the stationary frame 16. Mechanical restraints of other types may be substituted.

The stationary frame 16 comprises a box structure, which comprises upper rail 16U, lower rail 16L and end rails 16A and 16B. The carriage 15 comprises a downwardly extending panel to which is secured a power cylinder unit 100, which is constructed in accordance with one main feature of the present invention. The unit 100 is disposed lengthwise within the box frame 16 and includes a rod or shaft 26 which extends from both ends of the cylinder unit 100 to have its ends bear against the internal surface of the side walls 16A and 168.

To detect lateral movement of web 11 from its normal position, a sensing element is employed, the sensing element comprising a palm or feeler 37. The palm 37 includes a vertical rotary pin which is journaled in sleeves or bearings carried by an arm 40, the latter being carried by a rotatable shaft journaled in a bearing 42. The bearing 42 is carried at the upper end of a stationary bracket 43 mounted upon the stationary portion of the machine. A locking screw having a hand wheel 47 for adjustably securing bracket 43 to bracket 44 is provided. Thus, palm 37 is held in a fixed position relative to the stationary portion of the machine, but is free to swing or pivot vertically about arm to dispose its surface in alignment with the adjacent edge of the web 11.

An arm 46 is connected to the opposite end of the shaft through the bearing 42 and carries a block 48. The arm 46 is adjustably and pivotally connected to a generally vertical link 55.

At its opposite end, link is pivotally connected to an arm 57 which, in turn, is rigidly mounted upon a shaft 58 journaled in bearings formed integral with the stationary bracket 44. An arm 60 is rigidly secured to the opposite end portion of shaft 58 and the opposite end of said arm is pivotally connected to an end of a link 61.

A supporting plate 63 is secured to the movable earriage and carries a four-way valve 65. The structural features of valve 65 will be hereinafter more fully described, but in general it is manipulated by the rotation of a shaft which rotates in response to the pivoting of an arm 69 which is pivotally connected to the link 61. The valve 65 has two air pressure outlets connected by hoses 70 and 71 to opposite ends of the cylinder unit 100 to supply the motive power thereto. Mechanical or fluid operated systems, other than described herein, to transmit motion between palm 37 and arm 69 may be substituted. The valve 65 also includes an air pressure line inlet 79 (FIG. 2) for connection to a mill instrument air pressure line and an atmospheric air pressure outlet 78. The four-way valve 65 moves together with the movable carriage 15.

A better understanding of the operation of the valve 65 and cylinder unit 100 may be gained by reference to FIG. 2. In that figure, pipe 82 connects with a source of air or other compressible fluid under pressure. The

pipe 82 connects into a conventional filter 83 which is connected with a conventional pressure regulator 84 and which, in turn, connects with a lubricator 85. From the lubricator 85 an air pressure pipe 86 connects to a check valve 87. As will be explained in detail below, the check valve 87, while not strictly necessary for the successful practice of the primary features of the invention, is a highly desirable feature. Thus, fluid under a pressure determined by the regulator 84 feeds through the check valve 87 to the high pressure inlet 79 of the valve 65. The valve 65 has a rotor 90 which rotates or oscillates in response to the pivotal movement of the arm 69 (FIG. 1) and thus in response to the linked feeler 37 and web 1 l. Oscillation of rotor 90 alternately from the neutral position shown, serves to admit air under pressure to one and to vent air under pressure from the other of the lines 70 and 71, the vented line bleeding to atmosphere via the low pressure outlet 78.

As can also be seen in FIG. 2, the cylinder unit includes a piston 24 rigidly secured to the rod 26. A cylinder bore 25 is defined by a housing 27 and is enclosed by means of circular end plates 28, which have sealed bearings 29 for slidably receiving the shaft 26 and for allowing relative motion between the housing 27 and the fixed shaft 26 and piston 24. The cylindrical bore 25 is thus divided by the piston 24 into two air pressure chambers 30 and 31 which are in communication through respective inlets 70' and 71 with the pressure lines 70 and 71.

In accordance with a primary feature of the invention, the piston 24 is provided with a generally torus shaped cutout or circumferential recess 32 to define a hydraulic zone between the cylinder 27 and the piston 24. The recess 32 is preferably rectangular in longitudinal cross-section. Affixed to the inner surface of the cylindrical wall 25 of the housing 27 is a ring 35 which extends to the circumferential surface of the recess 32 and divides the hydraulic zone into two chambers 36-36, whose sizes respectively are varied complementally by the relative position of the piston 24 and housing 27, that is their combined volume remains constant. Fluid flow between the chambers 36 is governed by metering orifices 101 through the ring 35.

The oil in the hydraulic chambers 36 is maintained under pressure and any loss is replenished via the orifices 101 through an inlet 102 from an oil line 103. The oil line 103 preferably is connected through a check valve 104 to an oil line 105 fed from the air line lubricator 85.

The purpose of the check valves 87 and 104 is to prevent reverse flow of the fluids, both air and oil, should an air failure occur external to the web guide 10. Because the air can be exhausted at unequal rates from the cylinder on either side of piston 24, motion of the cylinder could be caused during an air failure which would prevent the cylinder or guide from stopping at its point of last correction under these conditions. The hydraulic fluid offers a resistance to motion when no power is applied to the air cylinder and the guide, therefore, tends to stay at its point of last correction during an air failure.

The oil line 105 is connected to the oil drain outlet of the otherwise conventional lubricator 85 and thus supplies oil to the hydraulic chambers 36 under pressure to insure that these are full at all times, and also to insure that any fluid which is lost at the seals of the piston 24 is replaced by oil under the same pressure as the air in the cylinder, thereby preventing entry of air into the hydraulic zone.

Referring now to FIGS. 3, 4 and 5, the preferred construction of the power cylinder unit 100 will be described. As shown, the housing 27 may include a cylindrical body 27A and a pair of longitudinally spaced tube sections 278 fitted therein. The head plates 28 are fitted into the ends of the body 27A against the sections 278 and held in place by a number of machine screws 110 about their circumference. The outer edge of each head plate includes a groove for accommodating a seal 111, while the inner or piston rod receiving bearing 29 thereof includes a pair of adjacent butspaced apart grooves 112 and 113 for receiving respectively a wiper seal 114 and a quad ring seal 115.

The piston 24 includes a generally cylindrical shaped body section 24B which is of an outer diameter somewhat less than the inner diameter of the tubes 27B. The body 248 is affixed to the piston rod 26 in any convenient manner and has end surfaces 248 which include an outstanding ring projection 24]. Seated around the ring projections 24P are piston rings 24R which are affixed to the body 248 by means of a plurality of machine screws 24M.

The piston rings form the end walls of the torus shaped cutout 32 of the piston 24 and provide an air-oil seal by means of an O-ring seal l16set in a groove formed in its outer surface.

The hydraulic zone dividing ring 35 is seated between and attached to the edges of the tube sections 278 and includes a groove in its inner surface in which a quad ring 350 is seated to form an oil seal between that surface and the outer surface of the piston body 248 which moves relative thereto. A plurality of orifices 101 are formed in the ring 35 to allow metered flow from one chamber 36 to the other.

As best shown in FIGS. 4 and 5, the oil pressure from the inlet 102' is communicated to the chambers 36 by means of a groove 119 on the outer surface of the ring 35 encircling the ring 35 and a plurality of passageways 121 therefrom to the mid points of the orifices 101 through the ring 35.

A number of potential inlets 102" may be formed in the outer portion of the cylinder body 27A to allow the oil inlet line 102 to be attached at any convenient location and to increase the number of applications (vertical, horizontal or other) for the cylinder 100. A plug such as the plug 120 may be used to close off the unused inlets or the passageway 119 may not be formed in the ring 35. The inlets plugged by plug 120 are also used to bleed air from hydraulic chambers 36.

Similarly, a plurality of air inlets 70, 71 may be provided to simplify the installation of the cylinder in different types of web guides. The air ports and oil supply ports are preferably at four points sequentially located 90 apart about the circumference of the housing 27.

OPERATION In overall operation, the web guide functions to realign a misalignment in the web 11 (FIG. 1) by shifting the position of the roller 12. This is done by sensing the magnitude and direction of misalignment by the position of the feeler 37. The block 48 functions as a counterweight to move the linkage connected to the palm 37 so that said palm lightly contacts and follows the edge of the web 11. In the normal position of the device, that is, when the web moves along the desired path, the four-way valve 65 communicates equal pressures to the lines 70, 71. The direction and amount of any displacement of the feeler 37 is communicated by the linkages including thearms 40, 46, the link 55, rotatable members 58, the arm 60 and linkage 61 to the valve arm 69. When the arm 69 is in its central position the pressure on each side of piston 24 is equal, being the same as the pressure in pipe 86.

However, when the web 11 deviates in either lateral direction from its normal path, palm 37 is either moved by the web edge or is caused to follow the web edge thereby moving the plam linkage, the arm 69 of valve 65 is moved and valve 65 thereby vents through line or 71 on one or the other side of piston 24.

The pivotal displacement of the arm 69 in direct response to the feeler displacement rotates the rotor (FIG. 2) causing the decrease in air pressure in one of the lines 70 or 71 (depending upon the direction of rotation of the rotor 90). This drop in pressure is comm unicated to the one or the other (but never both at the same time) of the chambers 30 or 31. This drop in air pressure causes a force to be applied to the cylinder housing 27 to tend to move it and thus the bearings 14, axle l3 and roller 12 (FIG. 1).

The movement of the housing 27 relative to the fixed piston 24 is resisted by the rise in pressure of the relatively incompressible hydraulic fluid in one of the chambers 36 and is damped and slowed by the relatively small size of the orifices 101. This reduces hunting or overcorrection by the piston 24. The cylinder unit is thus powered by a compressible fluid, air, which applies pressure between the cylinder head plates 28, and the piston body 24 to initiate linear movement. Between the piston body 24 and the same cylinder bore as used by the air cylinder a noncompressible fluid, oil, is maintained. The hydraulic sealing ring 35 divides the oil portion 36 of the cylinder. As the air causes movement of the piston, oil is moved from one side to the other through the metering orifices 101 in the ring 35 to allow movement. The same piston seals are used both to contain air and oil and to prevent intermixture between the air and hydraulic fluids.

This provides an air cylinder 1011) which is hydrualically dampened to give a smooth hydraulic cylinder motion and is contained in a common cylinder housing 27 having a single piston rod 26 which may be double ended as shown or may be single ended if desired. The speed of motion is controlled by the combination of air pressure, orifice characteristics, and oil viscosity. Further with each stroke of the cylinder the oil lubricates the piston tube wall making the unit 100 selflubricating, It provides a maximum of linear movement for minimum space requirement.

The piston unit 100 causes the roller 12 to be slowly moved until the web returns to its correct position or until the housing is moved to its limit of motion. In either case, when the web returns toits desired location the feeler 37 through the linkagereturns the valve to its neutral position in which the air pressure in each line 70, 71 is equal.

As the cylinder housing moves, the carriage 15 moves and hence bearing 14 shifts the "end of shaft 13 to cant or incline the roll 12 relative to the web 11. .It can readily be seen that when the cylinder'units housing and movable carriage thus .move, valve 65 moves therewith and consequently, although the palm linkage functioned to initiate the movement, the movement of the valve relative to the linkage functions to return the rotor 90 to its normal position. Hoence, there is no tendency for the device to perform an overcorrecting action, the device having, what may be referred to, as a self-zeroing action.

Although the device comprising the present invention is shown as controlling the path of travel of a substantially horizontally moving web, and wherein the carriage moves in a substantially horizontal manner to effect such control, it is to be understood that a substantially vertically moving web may also be controlled merely by disposing the mechanism at right-angles to its shown position. To effect the control of such a vertically moving web the carriage will, in response to the sensing mechanism, move in a substantially vertical manner. Similarly any intermediate angles may be provided for in practicing the present invention.

It is to be understood that the device comprising the present invention may be employed in guiding paperforming wires and screens, traveling blankets, belts and the like all of which are referred to as webs. For purposes of convenience and clarity, the four-way valve 65, which functions as a control valve, is referred to in the appended claims as a control valve".

ADVANTAGES OF THE INVENTION As should now be apparent an improved web guide has been described and its mode of operation detailed. It should also be now appreciated that the above described invention offers a number of advantages over previous web guides including that described in the aforementioned U.S. patent. It should be apparent that the unit 10 provides a larger air piston area and, therefore, more power is available for the web guide using essentially the same space.

The use ofa common single output rod prevents misalignment between the two rods required by previous web guides. Previously the air cylinder rods and hydraulic cylinder rods of such guides had to be parallel in these dimensions or the guide would bind.

Further, the combined cylinderunit has many less seals and wearing parts than previous units and more stability is insured because of the location of the air-oil seals and pistons to absorb thrust loading at the rods.

Because air may be bled from the cylinder at any point around the cylinder circumference this cylinder may be used in any position.

The construction allows for the use of high temperature seals of the Teflon and Viton types resulting in both lower friction and improvement of performance in high ambient temperature applications.

As the cylinder unit is positioned, the air cylinder tube is constantly being lubricated by the oil in the hydraulic cylinder. lt is, therefore, essentially a selflubricated cylinder and corrosion resistant materials may be used for all external parts: brass, bronze and stainless steels. Manufacturing difficulties in the'previous two-cylinder design made this much more difficult. The invention thus provides a more powerful web guide that is easier to construct and maintain.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. Web guide apparatus wherein a guide roll in surface contact with a traveling web is shifted in response to the movement ofa movable feeling device in contact with the lateral edge of the web, comprising the combination of a frame, a carriage movably mounted on the frame and carrying one end of the guide roll, a cylinder mounted on the carriage and movable therewith, a piston rod fixedly associated with said frame and extending through both ends of the cylinder, a double headed piston secured to said rod, slidably engaged in said cylinder and defining first and second chambers therwith, an area of reduced diameter around said piston between the ends thereof defining a third chamber between said piston and cylinder, means for supplying said third chamber with hydraulic fluid under pressure, barrier means for resisting flow of hydraulic fluid in said third chamber upon movement of said cylinder relative to said piston, valve means connected to said first and second chambers and having an inlet and an exhaust outlet, means for supplying said inlet with high fluid pressure, said valve means being operab le to supply fluid pressure to one of said first and second chambers while exhausting fluid pressure from the other of said chambers, and means connecting said movable feeling device to said valve means for operation thereof.

2. The apparatus of claim 1 wherein check valve means are provided on the inlet of said valve means for allowing flow of pressure fluid only into said valve means, whereby said cylinder is not moved by a sudden decrease in pressure fluid.

3. The apparatus of claim 2 wherein the means for supplying said third chamber with hydraulic fluid includes check valve means allowing flow only toward said third chamber.

4. The apparatus of claim 2 wherein the area of reduced diameter around-said piston is in the shape of a toms, and said barrier means comprises a ring member extending from said cylinder and sealably and slidably engaging the reduced diameter portion of said piston and dividing said chamber, said ring member having a restricted orifice therethrough. 

1. Web guide apparatus wherein a guide roll in surface contact with a traveling web is shifted in response to the movement of a movable feeling device in contact with the lateral edge of the web, comprising the combination of a frame, a carriage movably mounted on the frame and carrying one end of the guide roll, a cylinder mounted on the carriage and movable therewith, a piston rod fixedly associated with said frame and extending through both ends of the cylinder, a double headed piston secured to said rod, slidably engaged in said cylinder and defining first and second chambers therewith, an area of reduced diameter around said piston between the ends thereof defining a third chamber between said piston and cylinder, means for supplying said third chamber with hydraulic fluid under pressure, barrier means for resisting flow of hydraulic fluid in said third chamber upon movement of said cylinder relative to said piston, valve means connected to said first and second chambers and having an inlet and an exhaust outlet, means for supplying said inlet with high fluid pressure, said valve means being operab le to supply fluid pressure to one of said first and second chambers while exhausting fluid pressure from the other of said chambers, and means connecting said movable feeling device to said valve means for operation thereof.
 2. The apparatus of claim 1 wherein check valve means are provided on the inlet of said valve means for allowing flow of pressure fluid only into said valve means, whereby said cylinder is not moved by a sudden decrease in pressure fluid.
 3. The apparatus of claim 2 wherein the means for supplying said third chamber with hydraulic fluid includes check valve means allowing flow only toward said third chamber.
 4. The apparatus of claim 2 wherein the area of reduced diameter around said piston is in the shape of a torus, and said barrier means comprises a ring member extending from said cylinder and sealably and slidably engaging the reduced diameter portion of said piston and dividing said chamber, said ring member having a restricted orifice therethrough. 